kickoff vs get-go

kickoff and get-go both are nouns.

Word	Noun	Adjective	Verb	Adverb
kickoff	Yes	No	No	No
get-go	Yes	No	No	No

As nouns, kickoff and get-go are synonyms defined as:

Other synonyms of kickoff include beginning, commencement, first, offset, outset, showtime, start, starting time.

kickoff (noun)	get-go (noun)
(football) a kick from the center of the field to start a football game or to resume it after a score	the time at which something is supposed to begin
a start given to contestants
the time at which something is supposed to begin